The document discusses the limit test for chloride. It defines a limit test as a quantitative or semi-quantitative test to identify and control small amounts of impurities likely to be present in a substance. The limit test for chloride determines the allowable limit of chloride in a sample. It involves dissolving the sample and standard sodium chloride solution, adding nitric acid and silver nitrate, and observing any opalescence or turbidity after 3 minutes. The sample passes the limit test for chloride if the opalescence is less than or equal to the standard solution.

1. LIMIT TEST FOR
CHLORIDE
BY
PROF. TAUFIK MULLA
ASSISTANT PROFESSOR
DEPARTMENT OF PHARMACEUTICS
SPBC COLLEGE OF PHARMACY.

2. WHAT IS LIMIT TEST ?
Every product must be clinically safe for the use of human or animal.
Before formulation need to be verify that every compound/drug/solvent all are must be pure/free from
impurity.
As we know, if impurity present in product or drug leads to change physical, chemical property, also
change color, odour, taste also change therapeutic effect of drug and produce toxic effect.
So purchasing of pure chemical or making free from impurity is expensive and difficult process.
Indian Pharmacopoeia has provide certain limit of impurity if present in substance so we can used for
manufacturing process.
The limit of impurity expressed in term of PPM = 1 micro gm = 10-6 gm

3. • Limit = amount present in substance
• Test = investigation or examination
• Impurity = foreign substance present in compound
• Limit test = "Limit test is defined as quantitative or semi-quantitative test designed
to identify and control small amount of impurity which is likely to be present in the
substance. Limit test is generally carried out to determine the inorganic impurities
present in the compound.
• Importance of Limit test
To find out amount of harmful impurity
To find out permissible amount of impurity

4. APPARATUS USED FOR PERFORMING LIMIT TEST
• Nessler cylinder

5. LIMIT TEST FOR CHLORIDE
• The Chloride Limit Test is designed to determine the allowable limit of chloride contained in a
sample.
Principle:
Limit test for chloride is based on the reaction between sodium chloride or chloride ion with silver
nitrate in the presence of dilute nitric acid to form silver chloride, which appears as opalescence in the
solution.
NaCl AgN03 dil. HN03 AgCI NaN03
sodium chloride silver nitrate silver chloride sodium nitrate

6. • Reagent Preparations:
• Dil. Nitric Acid: 106 ml HN03 is diluted to 1000 ml with water.
• Silver Nitrate Solution: 5 9 of AgN03 is dissolved in 100 ml of water.
• Standard Sodium Chloride solution: Dissolve 0.05845 gm of NaCl in 100 ml in distilled
water.

7. PROCEDURE
TEST SAMPLE STANDARD SAMPLE REASON
Dissolve given sample in 10 ml of
distilled water and transfer the
solution in Nessler cylinder and
marked it as ‘T’
Take 1 ml 0.05845% w/v solution of
Sodium chloride in Nessler cylinder
and marked it as ‘S’
The aqueous solution will leach out
all the chloride ions present in the
sample and make them ready to
react with silver nitrate.
Add 10 ml of nitric acid Add 10 ml of Oil. nitric acid Dil. Nitric acid is added in limit test
of chloride to make solution acidic
and help silver chloride precipitate
to make solution turbid at the end
of process.
Dilute to 50 ml in Nessler’s cylinder Dilute to 50 ml in Nessler’s cylinder Equal volume of the solutions is
taken to compare the opalescence.
Add 1 ml AgNO3 solution. Stir
properly and keep aside for 3
minute.
Add 1 ml AgNO3 solution. Stir
properly and keep aside for 3
minute.
The Ag+ ions will react with CI- ions
to form opalescence of silver
chloride.
Ag + Cl = AgCI
Observe the opalescence/turbidity Observe the opalescence/turbidity Compare after 5 min.

8. CONCLUSION
• The opalescence produced in the sample solution should not be greater than standard
solution.
• If opalescence produced in the sample solution is less than the standard solution, the
sample will pass the limit test of chloride and vice versa.
• Opalescent means colorless or white / milky color
• Turbidity means the quality of being cloudy